Icons, windows and mice - The computer's new face

At the beginning, computer representation of pictures was by no means perfect. The first screens were oscillograph monitors which could display the graphs of functions used by mathematicians and engineers. This type of representation was used for other purposes early on: "Space war" on the PDP-1, which appeared in 1960, is regarded as one of the first computer games.

 

The first plotters were derived from oscillographs. Scientists could use them to draw the results of their computations as graphs. Video terminals appeared in the mid-1960s, and were capable of displaying alphanumeric characters. A built-in character generator converted the 128 characters of the American Standard Code for Information Interchange (ASCII) into electron beam movements. Fragments of lines and right angles were available to generate simple graphical elements. Laboriously, programmers used these to design frames, highlighting and underscores for the input boxes of the time.

 

All this changed abruptly with the emergence of the graphics screen based on picture elements or pixels. Pixels are stored in the computer's memory. Based on the format of the 35 mm photograph (4:3), a screen format of 640 x 480 pixels was initially implemented. Using one byte (8 bits) per pixel, it is possible to represent 256 colours.

Presenting data graphically compresses information. A number of pixels produce an icon, which stands for a function, a program or a document. Instead of a short eight-letter name, we see an easy-to-remember icon comprising 32 x 32 pixels. The fact that it is easy to recognize the icon and to activate it with a mouse resulted in a new way of operating computers. Directory trees and command lines on the operating system level were replaced by graphical user interfaces à la Apple Macintosh or Windows 95, using the "desktop metaphor". In this graphical representation, documents are kept in folders, moved to other folders or thrown into the trashcan for orderly users to empty at the end of the day.

 

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